Cryptopals Crypto Challenge Solutions in Go

Author: Mohit Cheppudira mohit@muthanna.com 2020

This repository consists of my documented Go solutions to all 6 sets of the original Cyptopals Cryptography Challenges (formerly known as the Matsano Crypto Challenges).

These challenges have been implemented as Go tests to make it easy to explore and debug.

Livestream

I've been livecoding these challenges on Twitch -- if you want to join in, watch at https://twitch.tv/11111110b.

Be warned: some of these sessions are looooooong!

The Files

• setN_test.go - Solutions to the challenges in set N.
• aes.go - My implementations of various AES operation modes (ECB, CBC, CTR), along with some block-size detection and cracking code.
• sha1/sha1.go - A modified implementation of Golang's SHA1 to tap and extract hashing state
• md4/md4.go - A modified implementation of Golang's MD4 to tap and extract hashing state
• prng.go - My implementation of the Mersenne Twister PRNG
• rsa.go - My implementation of RSA (keygen, encrypt, decrypt, sign, verify, pad, unpad). Uses OpenSSL to find large random primes.
• dsa.go - My implementation of DSA (keygen, sign, verify)
• pkcs7.go - Functions implementing PKCS7 padding and unpadding.
• english.go - English plaintext-detection using frequency analysis.
• bigmath.go - Modular arithmetic with big integers (exponention, cube root, ceil/floor division, etc.)
• helpers.go - Various helper functions across the codebase: hamming distance, blocksize detection, padding, etc.
• data/*.txt - Data files as part of each challenge.

To Run:

Note that some challenges have been disabled because they're very slow (e.g., timing attacks, brute force attacks, bleichenbacher98). You can re-enable them within the test as you need.

Run all challenges:

go test -v

Run a specific challenge:

# Run challenge 38
go test --run C38

# Run all challenges in set 5
go test --run S5